A novel method for transient leakage flow rate calculation of gas transmission pipelines

To objectively evaluate the consequences of the pipeline leakage and ensure the safe operation and reliable gas supply of the gas pipeline, it is necessary to calculate the leakage flow rate variations. A novel model for transient leakage flow rate calculation of gas transmission pipelines is proposed in this paper. Based on the pressure data collected at the upstream and downstream block valve rooms of the leakage position, the time for alarm signal and closure signal of block valves can be determined, and the leakage orifice can be calculated by the iterative method based on the collected data of the block valve rooms from alarm signal to closure signal. The leakage process is divided into two stages according to the time when the leakage occurred and two block valves were automatically closed, and the leakage flow rate at each stage is calculated based on the characteristic line method. The proposed method is applied to a real gas transmission pipeline in China, and the minimum detectable leakage orifice at different locations is calculated, and sensitivity analyses of leakage location on leakage flow rate calculations are conducted in detail.